Diesel particulate filter assemblies are one of many types of emission control technologies that lower particulate matter emissions. Typically, a diesel particulate filter assembly includes a housing containing a catalyst substrate consisting of a plurality of longitudinal passages. At each end of the substrate, alternate openings are closed, so that each passage is closed at one end and open at the other. Exhaust gases that enter the filter assembly through an unblocked opening must pass through the thin walls in order to exit the filter assembly. Particulate matter that is unable to pass through the walls is thereby filtered and prevented from exiting the filter assembly.
By trapping particulate matter as exhaust gases pass through the filter, diesel particulate filter assemblies are able to greatly reduce particulate matter emissions and assist in the compliance with increasingly stringent emissions standards. While filter assemblies are generally effective and easy to maintain, they require periodic cleaning to prevent blockage. If a filter assembly becomes blocked, the filter assembly, and even the engine, can become damaged through excessive back pressure.
Most trapped particulate matter can be removed from the filter assembly through regeneration. This involves heating the particulate matter to combustion or oxidation levels. Regeneration, however, does not remove all particulate matter. Remaining particulate matter, or ash, may become trapped in the filter assembly and may gradually build up and plug the passages of the substrate. This ash must be periodically removed to prevent decreased efficiency of the filter assembly.
One such method for flushing ash from a diesel particulate filter is disclosed in U.S. Published Application No. 2005/0011357. Specifically, a liquid is pumped through a filter from the outlet to the inlet. Ultrasonic waves, generated by an acoustic generator, are imparted in the fluid and assist in dislodging ash from the filter. This method, however, does not provide for direct coupling of the acoustic generator to the filter in order to increase the amount of ultrasonic energy propagated throughout the filter, and to avoid inconveniences presented by fluids.
The present disclosure is directed to one or more of the problems set forth above.